1. Field of the Invention
This invention relates to a process for the preparation of a cyclic ether containing an O-silylated hydroxyl group.
2. Prior Art
Recent widespread development of genetic engineering attracts people's attention to various kinds of nucleic acid derivatives as functional substances or pharmaceuticals. Thus, intensive studies are being made on derivatives of nucleosides constituting a basic skeleton of nucleic acids, as starting or intermediate materials for the production of nucleic acid derivatives. Technology developed up to date is primarily concerned with deoxyribonucleic acids. Whilst a deoxyribonucleoside contains a primary hydroxyl group and a secondary hydroxyl group in its molecule, a ribonucleoside in ribonucleic acids, which is now increasingly utilized, has three hydroxyl groups including one primary hydroxyl group and two secondary hydroxyl groups. Thus, as a starting material for the synthesis of RNA, a compound having its 2'-hydroxyl group previously protected similar to a deoxyribonucleoside is suited. A 2'-O-silylated ribonucleoside, which is important among others, has been hitherto prepared by a method in which a compound having its highly reactive primary hydroxyl group protected is first prepared. The other two hydroxyl groups are silylated and the product is separated by chromatography. With this method, however, it is difficult to improve selectivity so that the desired compound is only obtained by toublesome treatments.
Similar to the ribonucleoside, an aldopyranose compound has one primary hydroxyl group and a plurality of secondary hydroxyl groups. When only the primary hydroxyl group at its 6-position and the secondary hydroxyl group at its 4-position are to participate a reaction, it is desired that the other reactive hydroxyl groups be protected. However, there is no method which can easily introduce a protective group to the hydroxyl groups other than those at 4- and 6-positions.